The Bell Airacuda


The prototype Bell XFM-1 Airacuda. Its performance and reliability were never adequate for combat service. Image: Wikimedia Commons.

In the late 1930s, aircraft companies across the world were swept up in a wave of enthusiasm for ‘bomber destroyers’ – heavily armed interceptors that sacrificed agility for firepower.

Germany, France, the Netherlands, and Britain all produced their versions of the type, such as the Bf 110, Potez 630, Fokker G.I, and the Beaufighter. Nor was the United States immune to the trend, with the Bell Aircraft Corporation developing its own unique take on the concept: the YFM-1 Airacuda.

The prototype first flew in September 1937. It was an odd-looking aircraft, with twin pusher engines and a main armament of two 37mm gyro-stabilised cannon, one in front of each engine nacelle. Although each cannon had its own gunner, it was intended that they would normally be fired by the fire-control officer seated directly behind the pilot, who aimed them by an inverted periscopic sight projecting beneath the fuselage.

The gunners could also fire their own weapons, but their main duty was to reload the cannon with five-round ammunition clips, 22 of which were carried in each nacelle.

The pusher engines caused endless problems, one of the most basic being the risk posed by the propellers to anyone bailing out. The gunners were worst off in this respect, as they were directly in front of the propellers.

In theory, the pilot would feather both engines to allow everyone to bail out safely, but the flight manual stated that this would take up to six seconds. As one test pilot commented, ‘That’s a long time in my book.’ The problem was eventually cured by fitting explosive bolts to blow off the propellers in an emergency, but the engines had plenty of other flaws.

Overheating problems

Even in flight, engine cooling was barely adequate, but things were far worse on the ground. During the summer, it was often impossible to taxi out to the runway without the engines dangerously overheating, forcing each aircraft to be towed into position for take-off. It wasn’t uncommon for the engines to overheat in the air, forcing the pilot to make an emergency landing, after which they had to be shut down immediately, leaving the Airacuda stuck on the runway until it could be towed back to the hangar.

Reliability wasn’t helped by the electrical system – a test pilot described it as ‘a nightmare’. This was largely because the designers decided to use electrically powered fuel pumps, hydraulic pumps, and gun-stabilisation, rather than engine-powered systems.

The sheer amount of electricity required meant an auxiliary power unit (APU) had to be installed, which was driven by a powerful four-cylinder petrol engine. Unfortunately, the APU was prone to sudden failures, which would rapidly drain the battery, cutting off the engines and leaving the hapless pilot without power to lower the flaps or undercarriage.

A total of 13 aircraft were completed, which equipped a single squadron between 1938 and 1940. But, despite constant modifications, performance and reliability were never adequate for combat service. Surviving aircraft were used for ground-crew training, before being scrapped in 1942. •

Strengths: impressive firepower
Drawbacks: engine problems, dangerous pusher propellers, unreliable electrical systems